The hepatic and splenic storage iron, including the relative distribution between ferritin and haemosiderin, was estimated in 130 necropsies including normal accident cases and cases with a variety of diseases. The storage iron was also examined histochemically. It was found that in the normal subjects, on the average, approximately 400 mg. of iron was stored in these two organs, somewhat more than half being present as ferritin iron. Increased storage iron was found in some cases of infection, malignancy, and in blood and hepatic diseases, while low stores were present in other cases with malignancy and in polycythaemia vera. Although there was a slight tendency in infections and malignant diseases for more of the storage iron to be present as haemosiderin than normally, the most important factor affecting the distribution of iron between ferritin and haemosiderin was the total storage iron concentration. With total storage iron less than 500 mug. per gram of tissue, more iron was stored as ferritin than haemosiderin, and with values above 1,000 mug. per gram more was stored as haemosiderin. The behaviour of storage iron in this respect was very similar both in the liver and in the spleen. Although the histological and chemical estimates of the storage iron showed a general agreement there was much variation and histological examination of the tissues gave only a very approximate idea of the storage iron levels.

Journal Article↗

PubMedDate not supplied

Effects of iron deficiency and iron overload on manganese uptake and deposition in the brain and other organs of the rat.

Manganese (Mn) is an essential trace element at low concentrations, but at higher concentrations is neurotoxic. It has several chemical and biochemical properties similar to iron (Fe), and there is evidence of metabolic interaction between the two metals, particularly at the level of absorption from the intestine. The aim of this investigation was to determine whether Mn and Fe interact during the processes involved in uptake from the plasma by the brain and other organs of the rat. Dams were fed control (70 mg Fe/kg), Fe-deficient (5-10 mg Fe/kg), or Fe-loaded (20 g carbonyl Fe/kg) diets, with or without Mn-loaded drinking water (2 g Mn/L), from day 18-19 of pregnancy, and, after weaning the young rats, were continued on the same dietary regimens. Measurements of brain, liver, and kidney Mn and nonheme Fe levels, and the uptake of 54Mn and 59Fe from the plasma by these organs and the femurs, were made when the rats were aged 15 and 63 d. Organ nonheme Fe levels were much higher than Mn levels, and in the liver and kidney increased much more with Fe loading than did Mn levels with Mn loading. However, in the brain the increases were greater for Mn. Both Fe depletion and loading led to increased brain Mn concentrations in the 15-d/rats, while Fe loading also had this effect at 63 d. Mn loading did not have significant effects on the nonheme Fe concentrations. 54Mn, injected as MnCl2 mixed with serum, was cleared more rapidly from the circulation than was 59Fe, injected in the form of diferric transferrin. In the 15-d-rats, the uptake of 54Mn by brain, liver, kidneys, and femurs was increased by Fe loading, but this was not seen in the 63-d rats. Mn supplementation led to increased 59Fe uptake by the brain, liver, and kidneys of the rats fed the control and Fe-deficient diets, but not in the Fe-loaded rats. It is concluded that Mn and Fe interact during transfer from the plasma to the brain and other organs and that this interaction is synergistic rather than competitive in nature. Hence, excessive intake of Fe plus Mn may accentuate the risk of tissue damage caused by one metal alone, particularly in the brain.

Administration, Oral↗

PubMedDate not supplied

Transferrin binding by microvillar vesicles isolated from rat placenta.

Microvillar vesicles have been isolated from rat placentae. The vesicles have been characterized with respect to their microscopic appearance, their capacity to accumulate amino acids, and their enzyme activities. Alkaline phosphatase activity in the vesicle fraction was threefold greater than in the homogenate, and cytochrome c reductase activity was decreased fourfold. The vesicles were used to characterize transferrin binding to the trophoblast membrane in vitro. Transferrin binding was specific (K alpha = 8 X 10(7) M-1), and could not be replaced by apotransferrin. Apotransferrin binding showed lower affinity than the diferric transferrin, and did not appear to saturate over the range 0 to 500 micrograms/ml.

Animals↗